Low-foaming germicidal surfactantiodine compositions for cleaned-inplace equipment



United States Patent 01 Ffice 3,525,696 LOW-FOAMING GERMICIDAL SURFACTANT- IODINE COMPOSITIONS FOR CLEANED-IN- PLACE EQUIPMENT William Schmidt, Jamaica, N.Y., and Abraham Cantor, Elkins Park, Pa., assignors to West Laboratories, Inc., Long Island City, N.Y., a corporation of New York No Drawing. Filed Apr. 25, 1966, Ser. No. 544,852 Int. Cl. Clld 3/48, 9/50 U.S. Cl. 252106 13 Claims ABSTRACT OF THE DISCLOSURE A low-foaming surfactant-iodine composition for use in cleaned-in-place equipment, said composition consisting essentially of one part by weight of available iodine, 1 to 4 parts of an anionic surfactant containing a sulfonate grouping and selected from the class consisting of aralkyl sulfonates and N-substituted alkanoyl'taurates, .25 to 2 parts of an amphoteric surfactant containing a carboxylate joined through 1 to 4 methylene groups, including methylene groups interrupted by an ether group, to the nitrogen of a moiety selected from the class consisting of fatty alkyl substituted amine and Z-fatty alkyl substituted imidazolinium moieties, 12 to 50 parts of an acid selected from the group consisting of phosphoric acid, hydroxyacetic acid, and mixtures thereof, and aqueous-alcoholic diluent in an amount to provide in said composition an available iodine concentration of about 0.5 to 2.5%.

In the cleaning and sanitizing of dairy pipelines and other cleaned-in-place (C-I-P) equipment with surfactantiodine compositions the vigorous agitation and/or air injection encountered in circulating cleaning and sanitizing solutions amplifies the foaming tendencies of such solutions to the extent that general purpose surfactant-iodine compositions are inoperative in such equipment. Various efforts have therefore been made to provide special lowfoaming compositions for such uses, but the results heretofore leave much to be desired.

It is known, for example, that in compositions in which iodine is complexed with Water soluble alkyl phenolethylene oxide condensate, the foaming in ordinary use situations can be reduced by adding a small amount of.

water insoluble alkyl phenol-ethylene oxide condensate, but the least foaming of such compositions still foam inoperatively in dairy pipelines and other C-I-P equipment.

Two U.S. patents, Nos. 3,039,916 and 3,150,096, both assigned to applicants assignee are of special interest in that they recognize the special foam problem in C-I-P equipment and disclose a dynamic foam test method which is particularly effective in evaluating extremely low foaming (or essentially non-foaming) products intended for use in C-I-P equipment. The procedure for this dynamic foam test method is as follows:

150 ml. of the solution to be tested (a use dilution of a composition containing 6 to 25 p.p.m.. .of available.

iodine) is placed in a 500 ml. calibrated gas washing bottle with fritted cylinder. Using an air flow meter, the air flow is adjusted to 2 liters per minute and the foam height is read after equilibrium has been established at a temperature of 25 C.

When tested by this method, a com-positiomto be suitable for use in C-I-P equipment, must have a foam rating of less than 125 ml., and preferably below about 75 ml.

In U.S. Pat. No. 3,039,916 it is disclosed that in germicidal compositions wherein iodine is complexed with certain alkanoyl taurate compounds the foaming of use dilutions of such compositions can be reduced by including a small amount of a nonylphenol ethylene oxide condensate containing about 1.5 mols of ethylene oxide per mol of nonylphenol (which is water-insoluble). With such compositions, however, both the iodine and the water insoluble alkyl phenol ethylene oxide condensate concentrate in the foam, resulting in the formation of a highly insoluble brown tar. This tar coats equipment being cleaned preventing proper rinsing, and is frequently more difficult to remove than the original soil.

U.S. Pat No. 3,150,096 provides a low-foaming iodine composition intended for use in C-I-P equipment in which an anionic surfactant, sodium xylene sulfonate, is combined with a polymeric material, sodium polymethacrylate, in an acid system. While this composition is a very lowfoam composition, it has been found to be unsatisfactory as a cleaning composition when used in the field due to its poor detergent action. Furthermore, the iodine complexing is very poor, with the result that iodine odor of use dilutions makes such compositions impractical for use even as sanitizing rinses.

It is now discovered, in accordance with the present invention that extremely low foaming, or essentially nonfoaming, surfactant-iodine compositions can be prepared, which rinse clean without forming any brown tarry deposits, and which have good cleaning and detergent properties, by employing as surfactant component a mixture of certain anionic and amphoteric surfactants in the general proportions of about 1 to 4 parts by weight of anionic surfactant to each part by weight of amphoteric surfactant, with the 4:1 ratio being preferred in instances where both cleaning and sanitizing are desired; and further including in a composition an acidifying agent which will provide a pH below 3.5 in intended use dilutions of the compositions, i.e. dilutions containing 6 to 25 p.p.m. available iodine.

Anionic surfactants suitable for use in the new compositions are those characterized as containing a sulfonate group, with a preferred type being alkanoyl taurates of the formula:

R-N-CHzCHaSOaY Other suitable anionic surfactants include alkali metal alkyl aryl sulfonates such as C -C alkyl benzene and C C alkyl naphthalene sulfonates, of which sodium dodecylbenzene sulfonate (available as Nacconol N.R.S.F.)

is representative, and sodium dodecyl diphenyl ether di-' sulfonate (available as Benax 2A1).

-Amphoteric surfactants suitable for use in the new compositions are those characterized as containing a carboxylate moiety joined through 1 to 4 methylene groups (including methylene groups interrupted by an ether group) to a substituted amine moiety with a substituent of said amine moiety including a fatty alkyl group. Typical examples of such amphoteric surfactants include N-fatty alkyl B-imino and B-amino propionic acids and their salts of the general formula:

wherein R is fatty alkyl, R is the group CH CH COOX where X is H or a salt forming cation such as sodium, potassium, or ammonium, and R is selected from the group consisting of hydrogen, fatty alkyl (not necessarily the same as R) and R. Typical examples of such compounds, commercially available under the trademark Deriphat include:

Deriphat 151Sodium N-coco B-aminopropionate Deriphat 154Disodium N-tallow-B-iminodipropionate Deriphat 160-Disodium N-lauryl-B-iminodipropionate Deriphat 170CN-lauryl-N-myristyl B-aminopropionic acid Other suitable amphoteric surfactants are substituted imidazolinium compounds of the formula O CHZCOONa in which R is a fatty alkyl group containing 9 to 17 carbon atoms.

Compounds of this type, which are disclosed in US. Pat. 2,528,378 are commercially available under the trademark Miranol, typical examples being:

Miranol-CM-where R is C H derived from coconut acid Miranol-HMwhere R is C H derived from lauric acid Miranol-OM-where R is C H derived from oleic acid Miranol-SM-where R is C H derived from capric acid Miranol-DM-where R is C H derived from stearic acid Also suitable are the closely related imidazolinium compounds of the formula:

where R is C to C fatty alkyl, and alkali metal salts thereof.

In preparing the new compositions elemental iodine can be dissolved in a mixture of the surfactants with heating and agitation, but the iodine is more easily introduced as an aqueous HI-iodine solution (iodine dissolved in concentrated-45% or higherhydriodic acid) suitably containing about 57% available iodine. The concentration of available iodine in the composition can be varied considerably depending on the amount of dilution desired for preparation of use dilutions. For the practical dilution rate of one ounce per gallons of water (1 part composition to 640 parts by volume of water) an available iodine concentration in the range of .5 to 2.5% is generally preferred. Since compositions of somewhat higher or lower available iodine content can be employed equally well, by merely modifying the dilution rate, the relative amounts of surfactants and acid present are best considered with reference to the amount of available iodine.

The amount of acid in the new compositions, which can suitably be phosphoric acid, hydroxyacetic acid, or mixture thereof, can vary substantially with variations in available iodine concentration and intended use dilution. It is known that these acids protect the iodine in the presence of hard water components and organic soil, but

would render the compositions unsuitable for C'IP cleaning and sanitizing purposes. As a point of reference a composition containing 1.88% available iodine by weight, and intended for use dilutions of about 25 p.p.m. available iodine, should contain about 30 to 40% of acid (on a active basis). This amount of acid will provide a pH below 3.5 in most varying Water conditions from distilled water to F.D.A. hard water (Federal Register Sept. 19, 1956).

When the compositions are acidified with phosphoric acid it is desirable to employ conventional phase stabilizing components, i.e. to prevent any precipitation on standing, such as a lower alcohol or glycol. As much as about 20% of isopropyl alcohol or 10% by weight of propylene glycol can be employed, although as part or all of the phosphoric acid is replaced by hydroxyacetic acid, the alcohol or glycol can be substantially reduced, since compositions acidified with hydroxyacetic acid are more phase stable. This coupled with the lower corrosiveness of hydroxyacetic acid tends to offset the substantially higher cost of hydroxyacetic acid as the acidifying agent.

Having reference, thus, to compositions containing .5 to 2.5% available iodine, and intended to be diluted with water to use dilutions of about 6 to 25 p.p.m. available iodine the proportions of active components on a 100% active basis should be:

Parts Parts by wt.

It is significant to note that the proportion of total surfactant to iodine ranges from 1.25:1 to 6:1. This is a much lower surfactant to iodine ratio than is generally permissable when using nonionic surfactants; and the ability to use smaller amounts of surfactants is a factor contributing to the extremely low foaming characteristics of the new compositions.

The following examples show in greater detail some preferred cleaning and sanitizing compositions in accordance with the present invention for C-I-P equipment, as well as some significant data on the effect of pH on foaming tendencies of the anionic-amphoteric surfactant mixture; but it is to be understood that these examples are given by Way of illustration and not of limitation.

EXAMPLE I Active anhydrous percent, basis, wt. w./w. percent 15. 0 3. 45 0. 4 O. 38 Deriphat (97% active)- 1. 0 0. 97 HI-Iz solution (57% avail. I2) 3. 3 1. 88 Phosphorlc acid (75% active) 40. O 30. 0 Isopropyl alcohol 20. 0 20. 0 Water. 20.3

Total 100. 0

When tested for foaming at a l/640 use dilution using the dynamic foam test method above described this composition showed the following results:

Foam, inls. pH

Diluted in Distilled water- 40 2. 4 F.D.A. 100 p.p.m. hard water 6 2. 5

are obtained when the Deriphat 1 60 is replaced by an equivalent amount of Deriphat 151, 154 or 1700.

When tested for foaming at a 1/640 use dilution using the dynamic foam test method above described, this composition showed the following results:

Foam, mls. pH

Diluted in Distilled Water 50 2. 4 F.D.A. 100 p.p.m. hard water 14 2. 5

The slightly higher foaming than in Example I is of no consequence. This composition is equally effective in cleaning dairy pipelines and other C-I-P equipment.

Compositions of quite similar low foaming character are obtained when the Miranol HM is replaced by an equivalent amount of Miranol CM, DM, SM or DM.

EXAMPLE III A cleaning-sanitizing composition is prepared containing:

Active anhydrous percent, basis, wt.

w./w. percent Componenet:

Igepon CN42 (23% active).-- 15.0 3. 45

Nacconol NRSF (95% active) 0. 4 O. 38

Miranol HM (37% active) 5. 4 2. 0

111-12 solution (57% avail. I2) 3. 3 l. 88

Phosphoric acid (75% active) 40. 0 30. 0

Isopropyl alcohol 20. 0 20. 0 Water 15. 9

Total 100. 0

In 1/640 use dilutions this composition has a pH of 2.4-2.5, and when tested for foaming by the dynamic foam test method gives substantially the same low foam volumes as in Example II.

EXAMPLE IV The Igepon CN-42 as employed in Examples I and III is a preferred anionic surfactant for use in the new low foaming compositions, but in order to demonstrate the foam depressing effect as acid pH on other anionics the following comparative data is presented:

Solutions were prepared in distilled water containing 0.01% by weight of anionic surfactant, and other solutions were prepared containing 0.01% anionic surfactant and 0.005% amphoteric surfactant (Deriphat 160) providing a 2:1 anionic: amphoteric ratio. Portions of these solutions were adjusted to pH 2.6 and pH 7 using phosphoric acid, and sodium hydroxide as needed, and 100 ml. quantities of such pH adjusted solutions were placed in 250 ml. stoppered cylinders. These cylinders, clamped several at a time on wooden racks were shaken manually 20 times, and the foam volume read immediately after shaking. (While this type of foam test method is much less sensitive than the dynamic foam test method above mentioned, it is nevertheless effective for a quick comparison of foaming characteristics.) The comparative values expressed in ml. of foam are tabulated below.

Ml. foam It is significant to note that in all instances the amphoteric surfactant, while inducing as much or more foam at pH 7, caused a substantial reduction in foam at pH 2.6.

To better visualize the pH transition point comparisons 1 and 4 above were repeated with the anionic-amphoteric mixture at a number of intermediate pH values with the following results:

la 4a Igepon ON42 Nacconol NRSF us plus Deriphat 160 Deriphat 160 foam, m1. foam, ml.

EXAMPLE V A Cleaning-sanitizing composition is prepared containing:

Active anhydrous Percent, basis, wt. w./w. percent Component:

Igepon ON-42 (23% active) 15. 0 3. 45 Deriphat (97% active) 1.0 97 Phosphoric acid (75% active). 40. O 30. 0 111-12 solution (57% avail I2) 3. 3 1. 88 Propylene glycol- 10. O 10. 0 Water 30. 7

Total 100. 0

A solution of this composition 1/ 640 in distilled water showed a pH of 2.4. Separate portions of this solution were adjusted to different pH levels by addition of dilute NaGH solution and 100 ml. portions in 250 ml. stoppered cylinders were shaken to generate foam as described in Example IV, with the following results:

Foam, ml. (Shake method) 0 0 i 0 40 40 50 Foam, ml. (Dynamic test) 40 50 70 350 l Overflows test cylinders.

This clearly indicates that the advantageous low foaming properties of the new compositions are dependent on providing at use dilution a pH below about 3.5. Furthermore, since accurate check of pH in the field is impractical it is preferable to formulate compositions with sufficient acid to provide a pH below about 3.0 at recommended use dilution in all water normally to be encountered.

7 EXAMPLE VI A cleaning-sanitizing composition is prepared containing:

A 1/640 use diluion of his composition provides a pH of about 2.7 and has low foam characteristics similar to the composition of Example V.

EXAMPLE VII A cleaning-sanitizing composition is perpared containing:

Active anhydrous Percent, basis, wt. w./w. percent A 1/640 use dilution of this composition provides a pH of about 2.5 and has low foam characteristics similar to the composition of Example V.

Various changes and modification in the low foaming surfactant-iodine compositions herein disclosed will occur to those skilled in the art, and to the extent that such changes and modifications are embraced by the appended claims it is to be understood that they constitute part of the present invention.

We claim:

1. A low-foaming surfactant-iodine composition for use in cleaned-in-place equipment, said composition consisting essentially of (a) one part by weight of available iodine, (b) 1 to 4 parts of an anionic surfactant comprising an alkanoyl taurate of the formula:

*Where R is the radical C H CO, being an integer from 11 to 17, R is selected from the group consisting of hy-- drogen, lower (C to C alkyl and cyclohexyl radicals, and Y is seletced from the group consisting of hydrogen and alkali metal and ammonium cations (c) .25 to 2 parts of an amphoteric surfactant selected from the group con- OH CHgCOONa wherein R is a fatty alkyl group containing 9 to 17 carbon atoms, and compounds of the above formula wherein the substituted nitrogen has a single substituent the group CH CH OCH CH COOX wherein X is selected from the group consisting of hydrogen and alkali metal and ammonium cations, (d) 12 to 50 parts of an acid selected from the group consisting of phosphoric acid, hydroxyacetic acid, and mixtures thereof, and (e) aqueous alcoholic diluent in an amount to provide in said composition an available iodine concentration of about 0.5 to 2.5%.

2. A low-foaming surfactant-iodine composition as defined in calim 1 wherein the proportion of anionic surfactant to amphoteric surfactant is within the range of about 2 to 4 parts anionic surfactant per part by weight of amphoteric surfactant.

3. A low-forming surfactant-iodine composition as defined in calim 1 wherein the amount of acid is within the range of 15 to 30 parts per part by weight of available iodine.

4. A low-foaming surfactant-iodine composition as de fined in claim 1 wherein the anionic surfactant component includes a lesser amount of an alkali metal alkyl aryl sulfonate, wherein the alkyl group contains 6-16 carbon atoms.

5. A low-foaming surfactant-iodine composition as defined in calim 1 wherein said anionic surfactant also includes a lesser amount of a sulfonate selected from the class consisting of alkali metal C C alkyl benzene sulfonates and C -C alkyl naphthalene sulfonates.

6. A low-foaming surfactant-iodine composition as defined in claim 1 wherein the anionic surfactant is sodium N-cyclohexyl-N-palmitoyl taurate.

7. A low-foaming surfactant iodine composition as defined in claim 1 wherein the anionic surfactant is a mixture of sodium N-cyclohexyl-N-palmitoyl taurate and a lesser amount of sodium dodecylbenzene sulfonate.

8. A low-foaming surfactant-iodine composition as defined in claim 1 wherein the amphoteric surfactant is disodium N-lauryl-B-iminodipropionate.

9. A low-foaming surfactant-iodine composition as defined in claim 1 wherein the amphoteric surfactant is a compound of the formula:

10. A low-foaming surfactant-iodine composition as defined in claim 1 wherein the anionic surfactant is sodium N-cyclohexyl-N-palmitoyl taurate, and the amphoteric surfactant is disodium N-lauryl-B-iminodipropionate.

11. A low-foaming surfactant-iodine composition as defined in claim 1 wherein the anionic surfactant is a mixture of sodium N-cyclohexyl-N-palmitoyl taurate and a CHzCOONa 13. A low-foaming surfactant-iodine composition as defined in claim 1 wherein the anionic surfactant is a mixture of N-cyclohexyl-N-palmitoyl taurate and a lesser 9 10 amount of sodium dodecylbenzene sulfonate, and the am- 3,380,923 4/ 1968 Beach 252106 photeric surfactant is a compound of the formula 2,977,315 3/ 1961 Scheib et a1. 252--106 CH 3,244,636 4/1966 Reller et a1. 252106 2 N/ \CHZ 5 OTHER REFERENCES 011E234; I-CHzCHzONa I. N. McCutcheon: Detergents and Emulsifiers, 1967,

OH CH2COON3 I References Cited 10 LEON D. ROSDOI? Pnmary E'xammer UNITED STATES PATENTS P. E. WILLIS, Asslstant Exammer 3,039,916 6/1962 Neracher et a1 424 150 3,118,842 1/1964 Besser 252-106 252-407 

